Monobloc air-cooled internal combustion engine cylinder



Jan. 19, 1965 FISCHER E'rAl.. 3,156,053

NoNoLoc AIR-cooLEn INTERNAL coMBusTIoN ENGINE CYLINDER Filed Nov. 18,1963 3 Sheets-Sheet 1 INVENTORS Hans Fzlscher ISL'@ fried Meurer' JQ lasLiebe! BY A /u MM @fanolug s Jam. 19, 1965 H. FISCHER ETAL 3,166,053

MoNoBLoc AlN-,coman INTERNAL coMBusTzoN ENGINE CYLINDER Filed Nov. 18,1963 3 Sheets-Sheet 2 lNvENToRs Hans FASC/1er Sie fried Meurer" JulqusLzebel /dg elifT'TORN s Jan- 19, 1965 H. FISCHER ETAL 3,156,053

MONOBLOC AIR-COOLED INTERNAL COMBUSTIN ENGINE CYLINDER 3 Sheets-Sheet 3Filed Nov. 18, 1963 United States Patent O This invention relates to'amonobloc air-cooled piston engine cylinder for 'an internal combustionengine. In particular, this invention is directed to a monobloc cylinderhaving an integral liner forming the working surface for a piston. Thiscylinder is usable in all types of reciprocating machinery, but isparticularly applicable toan air-cooled internal combustion engine.Cylinders of this type are often composed of alight metal alloy andiitt'ed with a cast iron or steel liner. In view of the high thermalstresses currently permissible in automotive internal combustionengines, especially diesel engines, very high pressures and workingytemperatures occur and produce high stresses and steep temperaturegradients which must be accounted for. It is important that the lightmetal alloy used for the cylinder should be an alloy having good heatdissipation properties and, above all, has a suiliciently high strengthto ensure that the cylinderA head-portion of the monobloc can resist thehigh compression and combustion pressures in the cylinder.

A cylinder composed of a single light metal casting with aliner insertedor'pressed in the cylinder is well adapted to Vmeet these conditions.However, sucha light metal cylinder'has the disadvantage in thatcombined high tensile and bending stressesoccur at the transitionbetweenV the cylinder head portion and the cylinder portion of themonobloc which necessitates largecross-sectional areas in this region ofthe casting. This means that only short cooling iins can be used,especially in the case of multicylinder engines due to the necessarynarrow spacing between the cylinders in the central vertical planethrough the crank shaft. In other words, the cooling fins must be madeshorter between cylinders rather than being preferably circular. Thiscauses unequal heat dissipation and may result in thermal difficultiesfrom heat concentrations which, in turn, causes greater cylinderdistortionsthan in the' case where the tins were -truly circular. Inaddition, such tends to adect the stiffness ofthe Vcylinder inthe laneof the crank shaft.v Y

The object of this invention is to avoid such diculties by reducing thebending stresses in the transitional area between the cylinder headportion and the cylinder portion of the monobloc which, in turn, permitsa smaller cylinder diameter and longer cooling fins, or, alternatively,

a closer cylinder spacing.

In general, this invention provides that'the transitional area betweenthe cylinder head portion and the cylinder portion be relieved fromtensile and bending stresses by having the liner extended into thecylinder head portion and tightly joined to the head portion. Inaddition, this liner extension is designed so that the liner receives alarge portion of the forces occurring on the cylinder'head portion. Thismeans that the cross-sectional area of the cylinder can be made smallerand the cooling iins made larger, or a closer cylinder spacing can beused. Y Moreover, an additional iirm anchorage of the liner is obtainedby casting the liner in the cylinder head portion.

An improved feature of this invention isobtained by forming radiallyVdirected holes in the lliner extension,

which holes are lled with the cylinder material when the cylinder iscast around the liner. This forms an absolntely rm joint between theliner and the cylinder head 'Y anothermodication of the invention; and

a ing another modiiication of the invention;

FIGURE 4 is a view similar .to FIGURE Z-'andV show-` rice e PatentedJanf19, 1965 extension. Such-shapes givea larger surface contact areaand consequently lower stresses per unit of surface area, as well as apositive connective joint.

Intanother moditication of the invention, at least two studs or boltsare formed either integral with the liner or screwed to the top endofthe liner and preferably arranged diametrically across the liner.These bolts or studs pass through the cylinder head portion. A bridgemeans preferably formed vof steel rests on the center of the cylinderhead por-tion between the bolts and held by a nut threaded on the end ofeach bolt. This reduces deflectionof the cylinder head'portionto aminimum so that they are practically eliminated and the bending stressesin the transition zone between the cylinder`:head portion and thecylinder portion substantially disappear.V

e In a further modiiication of this invention, the bridge v meansbetween theV bolts is composed ofja housing for the valve rocker armsvand their ttings. As'the housing is hollow, it can be designed with acomplete stiiness with no bending and takes up fiection.

The means by which the objectsof the invention are obtained aredescribed more fullyVV with reference tothe accompanying drawings inwhich;

FIGURE l is av longitudinal cross-sectional view.

through the monoblocV cylinder of 'this invention;

`FIGURE 2 is a similar vie.

FIGURE 3 isl a View Simnar to FIGURE z'fand'showing another modificationof the invention;

a further modification of the invention; Y

FIGURE. 6 is a view similar to FIGURE Zwith still FIGURE 7 isa viewsimilar to FIGURE 2 showing yet another modiiication of the invention. gi

FIGURE 8 is aV transverse sectional lviewthrough the monobloc cylindershowing'the housing for the valve rocker arms. Y a

In FIGURE l, the liner 1 has cast around it a iinned cylinder 2 so thatit is integral withV the cylinder head.

The casting is preferably done by an aluminium vbonding process. Theintake port 4 and the exhaust port `5 are formed in the cylinder headportion 3. `Liner 1 has an extension 1a extending into the head portionso that theV casting is on both sides of the extension'and produces `asecurely placed or shrunk joint between the liner and formly around thecircumference. The cast cylinder material ows through these holes toform an additional con-tV nection between the liner and the headportion.V Y

In the modification of VFIGURE 3, the extension 1 is in the shapeY of adove-tail so that a Vdove-tail joint 7 is formed between theliner 1 andthe cylinder head por-` tion 3.

` In the modiiication of FIGURE V4,; the liner extension" 1d'isl shapedwith saw tooth serratious 8.1 The cast cylinder material xiows into theserrations during the casting the bending forces without deg` Qtaportion of HGRE l showing a modified form of the invention; f

' g The modication of FIGURE ;5 is similar q Y a v l Y so that a solidjoint isrformed between the liner and the cylinder, and the liner iscapable of effectivelyrtransmitting'the compression and combustionforces produced onthe cylinder head portion 3.

to Ythat of FIGURE 4 except that the liner extension 1e is machined toformstepped grooves 9.V 7 Y' Y In thernodications of FIGURESJYand 7,V atleast two bolts are attached to the top edge lfof liner 1, these bolts Apreferably being positioned diametricallyon the liner. In

FIGURE 6, the bolt 19a is threaded tothe top ofthe linerextension andpasses through theAVV cylinder headV portion t 3. vrThe exposed ends ofthe bolts extend through a bridge 11 Y which rests on the top ,surfacey14 of headportion 3.

' Threaded endsZ of the bolts receive nuts 13 so that the bridge 11 istightened against the cylinder head. Comequently, the gasV pressuresacting on head portion 3 are transferred through bridge 11 and bolts'10torliner 1 with theresult thatthe head portion 3 is Vstiienedand bendingstresses in the transition zone between head portion 3 and cylinderportion 2 disappear almost completely. Y

FIGURE 7 is similar to FIGJRE except that bolt 19a. is integral withliner "l'rather thanrbeingY threaded to the liner.

jFIGURE 8 is a modification of FIGURE 6 thebridge 11 being designed-toform a', housing for thevalve rocker armsY and their iittings. ForY thispurpose the Vbridge is formed with a cylindricalrextension 111 and a topcover. 15." The Yspace provided-bythe cylindrical extension accommodatesa camshaft actuating the valves 17,V 18 Vvia rocker arms 19,2% in theusual manner.V Theivalves 17,

'13 Vare forced against their seats', and associated rocker arms bynested coil springs V'21,' Z2 and 23,'. against springeretainersZIZG and27,28. u

i It isapparent thatv in reach, of these modiications, itis 24 `bearingVnotneeess'ary to increase'the cross-sectional area between head portion3 and cylindefrfportion 2 in care ofthe stresses occurring in this zone.

order to take Having now described the of the invention are obtained, weclaim:

1. A monobloc air-cooled internal combustion engine cylinder comprisinga cylinder liner, a single piece nned cylinder block Yportion andcylinder heady portion cast around both sides of said liner, and saidliner having an extension into said head portion for being tightlyconnected to said'head portion only where said head portion joins saidblock portion for taking combustion gas pressure stresses from 'saidhead portion. 2. A cylinder as in claim 1, further comprising radiallydirected holesrin said liner extension filled with cast cylindermaterial for forming an .additional connection be tween said liner andhead portion. Y

3. AV cylinder'as in claim 1,`furtlierv comprising-a dovetail jointYbetween said liner extension and said headV portion.

4. A cylinder as in claim 1, further comprising serrated rooves insaid-linerexter1sion filled with cast cylinder material.

5. A cylinder as in yclaim 1 further comprising da?,V metrically opposedbolt means joined to saidliner exfrj tension Vand passing through saidVhead portion, bridge means between said bolt means, and nuit meansthreaded to said-bolt means for tightening bridge means against. v saidcylinder head portion. f

f 6. A cylinder as inclaim'S, said bridge means comprisf v ing valverocker arm supporting means.Y

References .Cited by the Examiner RICHARD n..v/ILKINS'ON, Primm ExamiriYKARL ALBnECHTf, Examiner;

means by which the objects`

1. A MONOBLOC AIR-COOLED INTERNAL COMBUSTION ENGINE CYLINDER COMPRISINGA CYLINDER LINER, A SINGLE PIECE FINNED CYLINDER BLOCK PORTION ANDCYLINDER HEAD PORTION CAST AROUND BOTH SIDES OF SAID LINER, AND SAIDLINER HAVING AN EXTENSION INTO SAID HEAD PORTION FOR BEING TIGHTLYCONNECTED TO SAID HEAD PORTION ONLY WHERE SAID HEAD PORTION JOINS SAIDBLOCK PORTION FOR TAKING COMBUSTION GAS PRESSURE STRESSES FROM SAID HEADPORTION.